Have you tried net booting it? Setting up a RARP and TFTP isn't that
difficult and would rule out a broken CDROM.

No, haven't tried that. I guess it's a matter of principle at this
point- the darned thing should be firing up from the cdrom. I use this
box quite a bit for development purposes. I can fairly-painlessly
install FreeBSD or OpenBSD or Solaris 7, 8, or 9, with either complete
install CDs, or boot-only CDs that fetch the rest via internet.
Therefore, I have to rule out hardware issues.

There is one thing that comes to mind with a Solaris install not too
long ago, FWIW. I had to install on a CD-less Netra, and had to hook up
an external scsi CDROM to the box. The thing would not boot with the
standard command, 'boot cdrom'. After a LOT of looking around, I found
the exact command I needed:

boot /pci@1f,0/pci@1/scsi@8,1/disk@4,0:f
Perhaps this will help a brighter person than I to figure all this out?
Thanks,
Matt